Q. A body of mass 0.4 kg is whirled in a vertical circle making 2rev/s. If the radius of the circle is 2m, then tension in the string when the body is at the top of the circle is
A) 41.56 N
B) 89.86 N
C) 109.86 N
D) 115.86 N
Explanation
(d) Tension at the top of the circle
$T = m\omega^{2}r - mg$
$T = 0.4 \times 4\pi^{2}n^{2} \times 2 - 0.4 \times 9.8$
$= 115.86$ N
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.